Lathe



Nov. 3, 194 2. G. P. REED ETAL LATHE '3 Sheets-Sheet 1 Filed June 28, 1939 mm '"w.-%

' INVENTORS Nov. 3, 1942. GP. REED ETAYLY LATHE Filed June 28, 1939 3 Sheets-Sheet 3 INVENT R Md! a? 7 ATTORNEYS Patented Nov. 3, 1942 UNITED STATES PATENT OFFICE LATHE George P. Reed, Bridgeville, and Frederick K. Landgraf, Grafton, Pa., assignors to Flannery Bolt Company, a corporation of Delaware 1 Application June 28, 1939, Serial No. 281,580

work W, are fragmentarily indicated in the shaft 1 Claim.

The invention relates to the finishing of spindle-shaped articles in lathes. We have developed it in practical application to the manufacture of sun barrels, and in the taking of a finishing out upon the rough-cut outer surface of the barrel. Invention is to be found in apparatus. The objects in view are precision of the finishing cut attained with speed and with economy.

In the accompanying drawings Fig. I is a view in side elevation of the finishing lathe of the invention, showing a piece of work in place upon it. Fig. II is a view in perspective and to larger scale, showing a portion of the lath of Fig. I. Fig. III is a view in cross-section through the tool carriage in place in the lathe. The lathe is here shown to be free of a piece of work. The scale is substantially that of Fig. II. Fig. IV is a view in horizontal section, on the plane indicated at IV-IV, Fig. III. Fig. V is a fragmentary view in elevation and to yet larger scale, showing a cutter in engagement with the work. Fig. VI is a view in perspective, illustrating diagrammatically the operation of the apparatus of the invention. Fig. VII is a view in cross-section of the cutting tool.

Referring first to Figs. I and III, a lathe is here shown that includes abed, I, in which is mounted a pair of longitudinally extending, parallel rails, 2, of inverted V-shape in cross-section. At one end the bed carries in a housing 3 a rotatable head-stock 4, and toward the other end it carries a tail-stock 5, adjustable in position relative to the head-stock upon the rails 2. A tool carriage 6 is borne by and travels longitudinally upon the bed. On one side (the righthand side, Fig. III) the carriage rests upon and makes guiding engagement with one of the rails 2; on the opposite side it rests upon th horizontally disposed surface I of the bed. Thus the position of the tool carriage upon the bed is related to a single longitudinally extending member-the rail 2 on the right, of ridged or inverted-V shape.

The work W is essentially a rough-cut spindleshaped article. In this case it is a gun-barrel blank with finished bore and with rough-cut outer surface coaxial with the bore. Thework is secured at one end (in this case the breach end) to the head-stock 4, to rotate-with the head-stock. At the opposite end a plug 8 is set in the bore of the work, and through this plug the work makes rotatable engagement with the tail-stock 5. The adjustability of the tail-stock upon the bed allows assembly to be made. Means for rotating th head-stock 4, and with it the 9. The work so mounted rotates in unison with the head-stock, and on an axis of rotation coincident with its own axis.

In operation the work has no longitudinal movement. It rotates while the cutters, progressing in straight-line courses, advance longitudinally upon it. i

In the carriage 6 the cutting tools ID are mounted. There is a plurality of them (in this instance, four) spaced circumferentially and forming a cluster. They are held in positions equally spaced from th axis of work rotation, and for each cutter the other members of the cluster form the backing, holding the work, while the cutting operation progresses, to the tool. Each tool It] is rigidly borne in a block II The tool-carrying blocks II are pivotally mounted upon pins I2 'in an annular plate I3; and the plate I3 is rotatably mounted in the carriage 6. From the bed of carriage 6, an integral part of the casting of which the carriage is formed, rises the standard 60. This standard is provided upon one face with a nicely machined seat for the plate I3; th plate is held, to its seat by the keeper ring I4; and the standard is centrally ported, that the work may extend freely through. The mountings of the annular plate I3 in the carriage, and of the carriage upon the bed of the lathe are made with great accuracy, so that the plate is truly centered in the axis of the mounted work. The body of each tool-block II is slotted, as indicated at I5 with a parallel-sided slot. The slot extends radially with respect to the centre of turning of the block upon its pin I2, and obliquely with respect to the centre of th tool cluster. The plate I3 is provided with windows I8 and from the standard 69 pins I! extend through the windows and into the slots [5 in the tool-blocks. Pivoted upon these pins I! are blocks IS with opposite parallel sides, that fit nicely between the walls of the slots. It is manifest that, as the plate I3 is rotated upon its seat in standard 69, th movement of blocks it along slots I5 effects rotation of the tool-blocks II upon their pins I2 and a corresponding adjustment of the circumference to which the cutting edges of the tools I0 coincide. The windows I8 are suitably proportioned to permit such rota- Upon the periphery of plate [3 teeth [9 are formed; but it sufiices that the lower limb only of the plate be so provided with teeth, for required range of rotation is small. The teeth are worm-gear teeth, and they are engaged by a worm 20 that is formed upon a spindl 2!, which spindle is mounted in the carriage. The spindle extends transversely of the carriage and beneath the plate l3. It is rotatable, to rotat plate I3 and so to adjust the spread of the tools and to bring them to a cutting circumference of desired diameter. A hand-wheel 22 with a micrometer scal 23 are provided for effecting such adjustment.

Not only is the spindle 2i rotatable; it is longitudinally reciprocable also, against tension of a spring 24. The spindle carries a block 25, within which the spindle itself turns, and from the block an arm 26 extends. The machine bed I is equipped with a jig or sine-bar 27; and the spring 24 is effective to hold the spindle at the limit of its range of longitudinal reciprocation (the right-hand end, as seen, in Fig. III) with its arm 26 in abutment upon the sine-bar 21. As the face of the sine-bar deviates from parallelism with the rail 2, it is manifest that in carriage advance the spindle will be shifted longitudinally in one direction or the other. As the spindle is so shifted, the convolutions of worm 28 will act as a rack in engagement with the teeth I 9, turning plate i 3 and correspondingly changing the diameter of the circumference of cut of the toolcluster.

Suitable means (not shown) are provided for causing the carriage 6 to advance, at a rate suit ably related to the rate of rotation of the headstock.

A gun barrel of substantially uniform bore throughout, is commonly of maximum wall thickness at the breach end, and from the breach end the wall thickness diminishes (and, ordinarily, at non-uniform rate) to the muzzle end. In the practice of this invention the rough-cut blank is ordinarily subjected to a single finishing cut. The carriage 6 is retracted to starting position (at the extreme left-hand limit of its range, as seen in Fig. I), and a piece of work W, a rough-cut gun barrel, is secured in place, engaged at it ends by head-stock and tail-stock, and extending through the plat !3, the standard 60, and through the cluster of cutters that has been spread to permit of such placement. The cutters are by the turning of hand-wheel 22 brought to proper spacing; and a sine-bar 27 of proper profile is accurately placed upon and sei do not revolve about th axis of the work, but

continue in straight-line course, with the qualification, however, that the cluster opens as operation progresses, in response to the shift imparted to spindle 2| by the wedging action of the obliquely set face of the sine-bar upon the arm 26 borne by the advancing carriage. The cutters engage the work, as diagrammatically shown in Figs. V and VI and make a succession of spirally extending cuts, removing the rough surface indicated on the right and leaving the fin-- ished surface indicated on the left.

The particular form of the cutting edges of the tools is indicated in Figs. V and VI. Lathe tools for other purposes are, ordinarily, relatively sharply pointed, and do their cutting at the points. At variance with this, the tools of the invention are chisel edged. The bar of steel that forms the tool is convex and substantially cylindrical on the side [00 that in the assembly faces the Work (Figs. V, VI, and VII). The cutting edge is formed by shaping the bar at its end to a beveled surface l0! and by grinding the beveled end to a surface I02 that ordinarily is slight- 1y hollowed and ordinarily is not co-extensive with th beveled surface 10!. Th chisel edge is curved on an arc of long radius. The tool is about an inch wide. When the machine is in operation, only a fraction (about one eighth of an inch) of the curved cutting edge of the tool is in cutting engagement with th work. This is indicated at a--b, Fig. VI. Manifestly, as the clustered tools spread, the surface that is finished becomes a surface of increasing diameter, and, as the clustered tools move inwardly, the surfac finished by the tools becomes a tapered surface of diminishing diameter; and, manifestly, by the particular shaping of the jig, the finished surface may be a tapered surface of non-uniformly increasing diameter, and so the specification for a gun barrel may be satisfied. If the rough-finished gun barrel upon which the finishing cut is made in this machine be a barrel that already has received approximately the desired outer configuration increasing in diameter at a non-uniform rate from nozzle to breach, the bite 11-1) of the tool upon the work will in the progress of the finishing operation shift along the extended edge of the tool and, as seen in Figs. V and VI, in direction from left to right.

While the preferred organization is that shown and described, of a stationary lathe bed and an advancing carriage, it is manifest that the rela tive movement of these two parts is all that is essential, and that the tool-carrier might be stationary, and the lathe bed be reciprocaole in relation to it.

The machine, developed for the specific purpose of finishing gun barrels, is manifestly applicable to the finishing of spindle-shaped articles generally, Whether they be provided with bores or imperforate.

We claim as our invention:

In a lathe for finishing the outer surface of a gun-barrel blank to a surface of varying taper from the breach end of the barrel to the muzzle, such lathe including a tail-stock, a head-stock adapted to effect rotation of a blank supported against the tail-stock, a carriage equipped with a cluster of pivoted tools whose cutting edges engage the surface of the blank at circumferentially spaced-apart points, means for advancing the carriage longitudinally of the blank between the head-stock and the tail-stock, and means including a jig for turning the tools on their pivots and spreading the cutting edges in unison radially of the axis of the blank as the carriage advances; the invention herein described which consists in the provision in the tool cluster of tools having cutting edges that extend on convex arcs substantially in the direction of the length of the blank whereby in the finishing of the surface of a blank of varying taper, the bite of the tools upon th blank advances along the edge of the tool.

GEORGE P. REED. FREDERICK K. LANDGRAF. 

